Synthesis And Properties Of Red To Near-Infrared-Emitting Platinum Complexes With Functional Phenanthridine

In this master's thesis,the organic red/near-infrared(NIR)luminescent materials were classified according to the luminescence mechanism.At the same time,corresponding research strategies were given for the problems in the current research field,and the research progress was briefly summarized.In view of the problems such as the red-shift of the emission wavelength of red/NIR luminescent materials,low luminous efficiency,as well as serious roll-off of device efficiency.We designed and synthesized 10 molecules about red/NIR cyclometalated platinum complexes based on phenanthridine(PD)derivatives.Their single crystal structure,thermal stability,photophysical and electrochemical properties of the complexes were studied.A total of 7 molecules of 3 systems were applied to organic electroluminescent devices,and their electroluminescent properties were systematically studied.The following research results have been obtained:(1)A cyclometalated platinum complexes of TP-TFPD-Pt-acac,TP-TFPD-DPA-Pt-acac,and TP-TFPD-TrPE-Pt-acac were designed and synthesized.It was applied to the solution-processed organic electroluminescent devices A and device B,respectively.In device A,those electroluminescence(EL)wavelengths were all 654 run.The doping device based on the complex TP-TFPD-DPA-Pt-acac has the best performance,with an EQEmax of 2.95%and a luminance of 368 cd/m2.By optimizing the device structure with device B,and the corresponding electroluminescent properties at the doping concentrations of 5.0 wt%and 10.0 wt%were tested.The doping device of the complex TP-TFPD-DPA-Pt-acac has the best performance,and the EQEmax reached 3.07%at doping concentrations of 10.0 wt%.(2)Two new zig-zag typy di-and mono-nuclear platinum(II)complexes of(BuPh-BDIQ)Pt2(dpm)2 and(BuPh-BDIQ)Ptdpm were synthesized and characterized by using a zig-zag type cyclometalating ligand of 3,10-di(tert-butyl)-5,12-bis(4-(tert-butyl)phenyl)-benzodiisoquinoline(BuPh-BDIQ).The cyclometalated platinum complexes of(BuPh-BDIQ)Pt2(dpm)2 presented NIR electroluminescent emission in their doped polymeric light-emitting diodes.The highest external quantum efficiency of 0.97%and a radiant intensity of 146 ?W/cm2 were observed in the device at 2 wt%dopant concentration,which is higher than those values of the previous NIR-emitting di-nuclear platinum complexes constructed by cyclometalated ligands.Further more,the efficiency roll-off was efficiently inhibited.It indicates that high-efficiency NIR-emitting di-nuclear platinum complexes can be obtained by designing zig-zag type C^N-CAN tetradentate cyclo-metalating ligand with a big rigid planar saw band.(3)A novel dinuclear platinum(II)complex of TP-DPA2-PDIQ-Pt2-dpm2 as well as its corresponding mononuclear complex of TP-DPA2-PDIQ-Pt-dpm were synthesized and characterized by using a diphenylamine(DPA)cyclometalating ligand of TP-DPA2-PDIQ.The cyclometalated platinum complexes of TP-DPA2-PDIQ-Pt2-dpm2 presented the improved NIR electroluminescent properties with an emission peak at 720 nm and a shoulder at 785 nm in its doped polymeric light-emitting diodes.A high external quantum efficiency of 0.61%and a radiant intensity of 96 ?W/cm2 were observed in the device at 2.0 wt%doping concentration.At high current densities(100 mA cm-2),TP-DPA2-PDIQ-Pt2-dpm2 is more effective to suppressing device efficiency roll-off.By comparing the work in(2),it was found that the introduction of diphenylamine groups increases the molecular dipole moment,and at the same time,the non-radiative transition rate of the complex increases,so its efficiency decreases.(4)By changing the mechanism of donor-acceptor(D-A)and platinum ions in the molecule,a strong electron-withdrawing thiadiazole unit was introduced on the basis of the rigid PD group to construct a thiadipopyridinium(PDT)unit to enhance the D-A interaction of the system.The synthesized complexes TP-PDT-Pt-acac and TP-PDT-S-Pt-acac were analyzed by single crystal structure and found that the complex TP-PDT-S-Pt-acac was a hexatomic platinum complex.We further synthesized a hexatomic platinum complex TPA-BT-TPA-Pt-acac.Systematically studied the molecular configuration of the complexes TP-PDT-S-Pt-acac and TPA-BT-TPA-Pt-acac intramolecular and intermolecular interactions.The emission peaks of the complexes TP-PDT-Pt-acac and TP-PDT-S-Pt-acac are 765 and 753 nm,respectively.Interestingly,the complex TPA-BT-TPA-Pt-acac emitting wavelength reaches 802 nm.This is a kind of organic NIR emitting material with simple synthesis and adjustable emission wavelength to the near-infrared region(?>900 nm).